The long-term aim of this project is an understanding of auditory development/plasticity in normal children and in children having a history of otitis media with effusion (OME). Aims 1 and 2 concern the development of binaural temporal and spectral processing, respectively. Aim 3 concerns development and plasticity in the perception of speech for children who have histories of chronic OME. Aim 1 investigates developmental aspects of a newly identified important binaural temporal ability to take advantage of the favorable SIN ratios available in masking noise envelope minima. We will test two specific hypotheses: 1) this ability in children shows a protracted improvement that can be characterized in terms of the development of the binaural temporal window; 2) this ability can account for hitherto unexplained individual differences in the masking level difference (MLD) in adults and in children. The second specific aim investigates the ability to resolve and utilize across-frequency differences in binaural interaural time differences (ITDs). Goals are to develop efficient methods to characterize this ability and its development, and to test the hypothesis that this ability has a protracted development in children. We will also test the hypothesis that sensitivity to across-frequency differences in ITDs depends upon whether concomitant stimulus variables favor a synthetic or analytic mode of processing. In Aim 3 we will use a speech perception approach to investigate auditory development and plasticity under conditions of abnormal/unstable thresholds and spectral shape that occur with OME. These studies will test the hypothesis that spectral weighting and the ability to combine information from different frequency regions is abnormal in children with OME history, perhaps due to the fact that the spectral shape of speech information is abnormal and unstable for prolonged periods of time during auditory development. Psychoacoustic studies will use standard, adaptive testing techniques, and speech studies will determine percent correct for sentences presented either in quiet or in speech-shaped masking noise. All phases of the project will include age-matched control listeners. Data will be analyzed using analysis of variance and correlation procedures. [unreadable] [unreadable]